Misfire - 1990 Patrol GQ 3.0 Petrol

Submitted: Wednesday, Jul 21, 2004 at 19:11
ThreadID: 14880 Views:3910 Replies:7 FollowUps:17
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My 1990 Patrol GQ 3.0 Petrol developed a strange behavior the last 2 days. After a while driving the engine starts to misfire in low revs with load e.g. driving between 1000-2000 rpm up a hill. In the beginning it doesnt happen. I changed the fuel filter today without impact. The leads look good and the spark plugs are new (2000km) and properly gapped. The airfilter seems to be fine too. I also noticed a slight oil smell but that can also come from all the tools and stuff I have in the back of the car :-)

Any help would be very appreciated,
Reisender
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Reply By: Member - Dragan T (VIC) - Wednesday, Jul 21, 2004 at 19:26

Wednesday, Jul 21, 2004 at 19:26
Misfire...check that your coil is not overheating and that distibutor is in the order.
AnswerID: 68868

Follow Up By: reisender - Wednesday, Jul 21, 2004 at 19:35

Wednesday, Jul 21, 2004 at 19:35
How can I check if the coil is overheating? The distributor cap looks fine on the first look and wouldnt the misfire appear all the time if there was a problem with the cap?

Thanks for the help mate,
Reisender
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FollowupID: 329354

Follow Up By: Member - Dragan T (VIC) - Wednesday, Jul 21, 2004 at 20:00

Wednesday, Jul 21, 2004 at 20:00
Well, when it starts misfiring, stop, and feel the coil with you hand, you should be able to keep your hand on it. Well there is a bit more to distributor that a cap mate. Atough cap is the usually the problem, but you never know.
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FollowupID: 329363

Follow Up By: reisender - Thursday, Jul 22, 2004 at 18:51

Thursday, Jul 22, 2004 at 18:51
The coil is out of spec. It is 1.4 ohm instead of 0.8-1.0 so a god chance that it is the reason but def. a replacement. The cap and contacts are fine and cleaned now. The leads are all fine so are the plugs. So if the coild wont solve it I'll chekc the timing and then there aint a lot left to do ;o)
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FollowupID: 329466

Reply By: mr diamond - Wednesday, Jul 21, 2004 at 19:58

Wednesday, Jul 21, 2004 at 19:58
gday.
check your vac advance is working.
did you check your timing.(10 degree min)
your leads might look good but could play up under load.
try them and if no good let me know.
but does sound like plugs/leads
AnswerID: 68879

Follow Up By: reisender - Wednesday, Jul 21, 2004 at 20:56

Wednesday, Jul 21, 2004 at 20:56
I checked the leads the other day just for fun but not seriously. they seemed to be ok but I'll give them a full check tom. The timing is on my list too but is it possible to change so quickly from one day to another?

Thx for the help mate,
Reisender
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FollowupID: 329371

Follow Up By: mr diamond - Wednesday, Jul 21, 2004 at 21:21

Wednesday, Jul 21, 2004 at 21:21
the rb 30 is renound for vac advance siezing.
if that siezes up there goes your timing.
to check your vac advance is as easy as where the hose comes from the dizzy to the pipe on the lhs of the motor pull it of and suck on it you should hear the advance unit in the dizzy clicking.
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FollowupID: 329375

Follow Up By: reisender - Thursday, Jul 22, 2004 at 00:49

Thursday, Jul 22, 2004 at 00:49
okydoky on the checklist :o)
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FollowupID: 329402

Follow Up By: reisender - Monday, Jul 26, 2004 at 16:37

Monday, Jul 26, 2004 at 16:37
It was the coil. Changed it and I didnt have a misfire for a couple of days now.
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FollowupID: 329972

Reply By: Member - Dragan T (VIC) - Wednesday, Jul 21, 2004 at 20:02

Wednesday, Jul 21, 2004 at 20:02
Mr jewel is right.. I have assumed that you have tuned your engine the way it should be!
AnswerID: 68880

Follow Up By: reisender - Wednesday, Jul 21, 2004 at 20:57

Wednesday, Jul 21, 2004 at 20:57
Yeah I am going after that too but I hoped there was a simple answer :o)
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FollowupID: 329372

Follow Up By: reisender - Monday, Jul 26, 2004 at 16:37

Monday, Jul 26, 2004 at 16:37
It was the coil. Changed it and I didnt have a misfire for a couple of days now.
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FollowupID: 329973

Reply By: Moz - Wednesday, Jul 21, 2004 at 21:09

Wednesday, Jul 21, 2004 at 21:09
G'day reisender,
I agree with above, sounds like a coil breaking down as it heats up or
possibly a crank angle sensor in the distributor.

Moz
AnswerID: 68899

Follow Up By: reisender - Thursday, Jul 22, 2004 at 00:48

Thursday, Jul 22, 2004 at 00:48
Sound likely :( I hope not coz they arent that cheap.
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FollowupID: 329401

Follow Up By: reisender - Thursday, Jul 22, 2004 at 18:50

Thursday, Jul 22, 2004 at 18:50
The coil is off the specs (1.4 ohm instead of 0.8-1.0) so I'll replace it as soon as I get one. The rest worked out so far. Just left to check the timing but the coil is a good bet now :)
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FollowupID: 329464

Reply By: Member Eric - Wednesday, Jul 21, 2004 at 21:19

Wednesday, Jul 21, 2004 at 21:19
I cant understand why your not looking at plugs also . nothing to say you havent got faulty plugs also . I would be looking at leads with a multy meter and checking resistence , especialy the coil lead
AnswerID: 68904

Follow Up By: reisender - Thursday, Jul 22, 2004 at 00:47

Thursday, Jul 22, 2004 at 00:47
The leads will be checked first thing tomorrow and the plugs are just new and didnt make any trouble so I thought they are ok but if I cant find anything I'll have a look.
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FollowupID: 329400

Follow Up By: reisender - Monday, Jul 26, 2004 at 16:37

Monday, Jul 26, 2004 at 16:37
It was the coil. Changed it and I didnt have a misfire for a couple of days now.
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FollowupID: 329974

Reply By: Brew69(SA) - Wednesday, Jul 21, 2004 at 21:20

Wednesday, Jul 21, 2004 at 21:20
Hi mate, i have the 4.2 petrol but the symptoms you are describing could be anything. Do you have more than one fuel filter?(some people will fit another one closer to the tank) The leads sometimes behave well when cool and when they heat up will misbehave. You said you have checked plugs. Check all the contacts on the inside of the distributor cap for carbon build up. Points? I changed my coil for a Bosch Gt to get more spark.Timing? Also how long has it been since you have adjusted the valve clearances. They should be reset every 60 000k's. This was the cause of my car missing last time. Good luck mate
AnswerID: 68905

Follow Up By: mr diamond - Wednesday, Jul 21, 2004 at 21:23

Wednesday, Jul 21, 2004 at 21:23
unfortunutly the 3ltr rb30 gq is a pain in the butt.
no points no crank angle sensor and the coil is a one of a kind $250.
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FollowupID: 329377

Follow Up By: flashnick - Wednesday, Jul 21, 2004 at 23:48

Wednesday, Jul 21, 2004 at 23:48
Nissan 4.2 and rb30 very different - much less maintence on RB30 no adjustments necessary - no points no tappet adjustments - most likely spark plugs breaking down - bosch plugs can break down - dont ask me why however NKG spark plugs most reliable, -- coil on RB30 almost bullet proof usually replaced in error whilst looking for other problem. If miss is at low revs when accelerator pressed down - most likely plugs breaking down (they dont have to be old for this to happen either)

cheers Nick
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FollowupID: 329395

Follow Up By: reisender - Monday, Jul 26, 2004 at 16:37

Monday, Jul 26, 2004 at 16:37
It was the coil. Changed it and I didnt have a misfire for a couple of days now.
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FollowupID: 329975

Reply By: Member - Mark S (WA) - Thursday, Jul 22, 2004 at 19:17

Thursday, Jul 22, 2004 at 19:17
check for any leakage around the fuel pump. rgds
Slow down and relax......

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AnswerID: 69084

Follow Up By: reisender - Monday, Jul 26, 2004 at 16:38

Monday, Jul 26, 2004 at 16:38
It was the coil. Changed it and I didnt have a misfire for a couple of days now.
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FollowupID: 329976

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